Process of treating substances carrying sulfur and metals.



New York,

UNITED STATES ARTHUR S. DWIGHT, OF NEW YORK, N. Y.

PROCESS OF TREATING SUBSTANCES CARRYING SULFUR AND METALS.

No Drawing.

This invention relates to the sulfiding of I one or more metal components of an artificially produced mass of metalliferous material, in order that the sulfids produced may be advantageously employed at a subsequent stage of treatment for securing the metal values desired to be recovered; and it has for its object to conserve the sulfur component of sulfur-carrying compounds, such for example as natural sulfid ores of iron and copper, in order that a larger proportion of the original content of sulfur may be advan tageously utilized than has heretofore been available.

For brevity, and for the purpose of referring to some body as a type of a large class, it may be said that the invention is particularly well adapted for use in the treatment of ores containing metal bodies,

which, for economy, must go through a matte-forming stage of treatment preliminary to the final extraction and recovery of the metal or metals sought.

And, still further for the sake of brevity, in referring at the outset to a specific instance where my invention may be employed, it can be stated that it is well adapted for the treatment of copper ores or copper-bearing masses; and that metal will be referred to, typically, as the one sought to be recovered, for the purpose of having the invention clearly understood As an aid to such understanding ters will be prelimmarily referred to before particularly describing my improved method for treating materials such as aforesaid in carrying out my invention.

It is well known that sulfur exercises a very important function in the pyro-metallurgical treatment of copper ores, by reason of the strong aflinity which it possesses for the metal copper; for as long as suflicient sulfur is present and available, the copper will be preserved against all oxidizing tendencies that might cause it to be carried away by the slag and thereby lost, the affinity between copper and sulfur being Specification of Letters Patent.

, a few well known mat- Patented Aug. 28, 1917,

Application filed March 5, 1914. Serial No. 822,694.

stronger than that between copper and oxygen.

It is also well known that the aliinity betweeniron and sulfur while active and strong, is less than that between copper and sulfur; while the affinity between iron and oxygen is greater than that between copper and oxygen. matte' (FeS) is largely employed, with ad vantage, incopper smelting, for the purpose of cleaning the slag of the copper which may be contained therein, either as metallic cop per, copper oxid, or copper silicate. Most copper ores suitable for smelting, such as the sulfids of iron and copper, contain a superabundance of sulfur,'part of which has to .be eliminated before the smelting of'the ore can proceed along economical lines. This 'elimmation of sulfuris usually efiected by some process of roastingthe ore. In these ores and some other compounds, a part of the sulfur component is in unstable combination and may be driven ofi simply by the application of heat, oxygen being excluded, in the form of vapor of sulfur which may be subsequently collected in solid form as flowers of sulfur. The portion of sulfur that may be thus easily driven off is designated as the unstable atom ofsulfur, and in the ores referred to amounts to from one-fourth to onehalf of the total sulfur content. The balance of the sulfur remaining after the unstable atom has thus been driven off, is found to be in fixed or stable combination with the metal,

Because of these facts iron smelted, forms, with the metal, what is known as a matte.

It is well known that there are available to the metallurgjst large quantities of'copper-bearing material which are so deficient in sulfur that they cannot be economically smelted under present ordinary conditions, because of the difficulty of properly cleaning the slag and of securing a matte of the proper quality. For, without the sulfur, the loss of valuable metal in the slag is so great as to practically prohibit the effort to profitably secure it. This deficiency in sulfur may exist in the ores in their native condition, as for instance the oxid and the carbonate ores, or may be the result of heat applied to sulfid ores at a preliminary stage, as in roasting or while sintering, which drives off the unstable sulfur atom and leaves too low a percentage of this element, so that there is not produced a matte that will thoroughly clean be constantly borne the slag. It has therefore heretofore been the practice in treating these copper ores deficient in sulfur, to mix therewith ores rich in sulfur where this has been practicable;

.but the cost of obtaining such sulfur-bearing and the percentage of sulfur in the resulting product can be brought to approximately any predetermined proportion necessary to putting the copper or other metallic ingredient which it is desired to recover into the required condition for smelting and subsequent refining treatment. There are numerous ways in which my invention may be carried out, of which I w1ll mention severalas being typical.

I have already referred to thefact that there are large quantities of native ores deficient in sulfur and which therefore cannot be profitably smelted, according to the processes heretofore in vogue, for the recovery of the copper without an undue loss of that metal in the slag. But it is a striking fact that in many cases there is actually present in these ores enough sulfur for forming a matte that will clean the slag, provided means were known for conserving the sulfur that they do contain, heretofore been driven or and lost in the earlier stages of treatment, that is, when the ore was roasted or even simply heated. I have discovered and proven that if sulfur ores such as referred to, deficient in sulfur, be pulverized and intimately mixed with a metal having a strong chemical affinity for sulfur, such as iron or copper, in a finely divided condition, as in the form of metal filings, and the entire mixed mass be raised to a bright red heat, free oxygen being excluded, the unstable atom of sulfur instead of distilling off as usual, will promptly and actively unite with the added metal and form a stable sulfid, with little or no loss of sulfur, as is evidenced by the lack of sulfur fumes during the treatment and also by chemical analysis of the product. This product becomes pasty at a comparatively low temperature, and advantage may be taken of this fact to cause the particles of the mass to agglomerate together to form balls or coarse lumps.

This coarse mechanical condition is favorable to certain processes of smelting, such as but which in part has meagre the blast furnace process; but the agglomerating tendency maybe avoided if desired, and the product left in the original pulverulent condition, which is more suitable for smelting in reverberatory furnaces. If agglomeration is desired this may be facilitated by subjecting the mass to slight compression while still hot.

Where the added metallic element is not readily available in its metal form, its oxid may be utilized as follows. The oxid and fine carbon, such gether and brought to the proper temperature to reduce the oxid, and then when this temperature has been reached and reduction is taking place, the fine sulfur-bearing ore to be treated is rapidly mixed therewith, air being excluded as completely as possible, and the temperature raised or maintained at a bright red heat. Under these conditions the unstable sulfur atom driven off by the heat actively unites with the nascent metal, as it is liberated from itsoxid, and forms a relatively fixed sulfid, the oxygen set free uniting with the carbon of the mixture. The resulting product is like that already described.

It will be understood that either of the methods of treatment just described may be employed with sulfid ores containing any proportion of sulfur.

The principal components of mixtures such as have been referred to are today found in large quantities, not only in native condition, but as by-products of other operations.

Thus zinc residues, a pulverulent product of zinc smelters, contain not only a large percentage of fine carbon, but also a relatively large amount of metals, such as iron, copper, lead and others in minor percentages; and I have succeeded in utilizing and making valuable this product by mixing it with sulfids containing a volatile or unstable sulfur atom, either as concentrates, or in native condition, and causing the reactions to take place which have already been described, causing the unstable element driven oif by heat to unite with the metal or metals of the zinc residues, forming a stable compound or compounds that may be utilized to advantage as a component of the subsequently formed matte.

As another instance of applying my in vention to the utilization of a by-product, I have succeeded in making available pyrites cinder, a by-product in sulfuric acid manufacture, composed largely of iron oxid together with more or less copper and other metals. This I take in pulverized form, resulting either from artificial comminuting or burning during the acid manufacture, and mix it with fine carbon and raise its temperature to a bright red heat, causing the metallic oxids to be reduced. I then add and as coal dust, are mixed tov ing a metal that has a strong 50 afiinity for sulfur,

mix therewith a metallic sulfid, as iron pyrites, bringin or maintaining the general mixture to a %right red heat. This results in completely fixing the volatile or unstable sulfur atom of the sulfid so that practically all of the sulfur of the mass is conserved in such a way that when the resulting product is later subjected to smelting operation a matte is formed that can be, with great advantage, utilized in copper smelting operations.

lVhat I claim is 1. In the treatment of sulfur bearing ores and metallurgical products containing an unstable sulfur component, for the purpose of obtaining the desired metal therefrom by subsequent smelting, the process described which consists in commingling with a mass of the said material a a metal that is active in matte forming, and causing, by the action of heat, the said unstable sulfur component to become disassociated and free from the metal in the first aforesaid mass, and to then unite with the metal of the said second mass to form a matte compound, under conditions unfavorable to the oxidation of the sulfur.

2. The herein described process of conserving the sulfur component in ores and metallurgical products and utilizing it in smelting, which consists in mixing pulverized sulfids with finely divided material carrying a metal that possesses a strong afiinity for'sulfur, of heat, the unstable sulfur atom carried by one component of said commingled mass, to pass to and unite with the metal aforesaid of the other component, and subsequently subjecting the resulting product to a smelting operation.'

3. The herein described process of treating ores and metallurgical products contain ing sulfur in unstable combination for-the purpose of conserving the sulfur and utilizing it in combination in subsequent smelting operations, which consists in mixing a sulfur-bearing material, while in a pulverized condition, with. a pulverized material carryaflinity for sulur, bringing this mixture to a red heat, whereby the unstable sulfur component of the mass is separated and caused to unite with the metal, andutilizing the sulfid thus formed in subsequent smelting operations.

4. The herein described process of treating ores and metallurgical products containing sulfur in unstable combination, for the purpose of conserving the sulfur and utilizing it in combination in subsequent smelting operations, which consists in mixing a finely subdivided metallic sulfid with a finely subdivided oxid of a metal that has a strong bringing this mixture to a red heat under conditions causing a re ducing of the oxid, whereby the elements of second mass carrying and causing, by the action .commingld therewith, of

order to prevent the loss of such the oxid are disassociated and the unstable I sulfur atom set free at substantially the same instant of time, causing the sulfur to unite with the free metallic element and it in combination in subsequent smeltingoperations, which consists in mixing a mass of pulverized metallic oxid and carbonaceous material, the metal of which oxid has a strong affinity for sulfur, bringing this mixture to a heat sufficient to cause a reducing of the oxid, and mixing with the first said mixture while the reduction of the oxid is taking place a mass of the said sulfur-bearing material in a finely divided condition and maintaining the heat in the absence of an oxidizing atmosphere, whereby the unstable atom of the sulfur of the last added mass is freed and unites with the freed metal of the first mass, forming a matte compound, and subsequently utilizing the said matte in ore smeltin operations.

6. The herein described process of treating ores and metallurgical products containing an. unstable sulfur component, which consists in mixing a finely subdivided mass of such material with a finely divided mass of material carrying a metal'that possesses a strong aflinity for sulfur, causing, by the action of heat, the unstable sulfur atom carried by one component of the 'commingled mass to be driven off and pass to and unite with the metal aforesaidof the other component, subjecting the mass while ina pasty condition from the action of the heat to which it was subjected, to pressure to cause its particles to cohere into masses, and subsequently subjecting such masses to a smelting operation.

7 The herein described process for treating a composite mass containing a body of sulfid material with a relatively high percentage of sulfur and a body, intimately material capable of being sulfided, it consisting in subjecting the composite mass containing the two intimately commin-gled bodies to heat in a non-oxidizing atmosphere, separating vpart of the sulfur from the first aforesaid body, and causing it to unite with the parts of the second body which are susceptible of q being sulfided.

8. The process of treatingores and metallurgical products carrying sulfur, a portion of which is in unstable combination, in unstable portion of sulfur, which consists in heating the mass and causing the unstable sulfur component to becomeadisassociated, and at the same time and in intimate association with the said mass causing an oxid of a metal having a strong affinity for sulfur to be reduced by the action of carbon, and cansing the freed sulfur to unite with the nascent metal, whereby a stable compound of the metal and sulfur is formed available for use in subsequent stages of treatment.

9. The process of treating ores and metallurgical products carrying sulfur in unstable condition, which consists in mixing such material in finely subdivided condition with a finely divided oXid of a metal having an afinity for sulfur and also with a reducing agent, and subjecting the mass to va suitable temperature in a reducing atmosphere whereby the oxid is reduced and the metal-in a nascent state caused to combine with the unstable portion of the sulfur and becomefixed in the form of a stable sulfid adapted to be used in subsequent stages of treatment.

In testimony whereof, I afiix my signature, in presence of two Witnesses.

ARTHUR S. DWIGHT. Witnesses HENRY J. STEHLI, JoHN Knox. 

